In making decisions regarding the focus for grammar teaching, ESL instructors may take into consideration errors that appear to result from the influence of their students' first language(s) (L1). There is also evidence from language acquisition research suggesting that for some grammatical features, learners of different L1 backgrounds may face similar types of challenges. This article examines the issues of L1 influence and common developmental patterns in the domain of verb tense and aspect. The first part of the article provides an overview of some of the tense-aspect learning challenges faced by learners in general. The second summarizes findings from a study that compared the acquisition of the simple past in English by Japanese and French-speaking learners. In the final section, teaching suggestions, based on the insights gained from acquisition research, are offered. The different activities presented all focus students' attention on the contextual factors which motivate choices about the most appropriate tense-aspect forms for conveying intended meanings.